Hypoxia inducible factor 1alpha--fracture repair

描述(摘自申请表)：尽管信息丰富 关于骨折修复过程中的缺氧和血管生成，重点是 负责这些关键早期过程的分子事件仍然未知。 随着分子生物学的最新技术进步和 数以千计的基因的鉴定，现在可以更清楚地 研究作为骨折修复过程基础的精确分子事件。 从本质上讲，我们坚信关键的早期进程，包括 缺氧和血管生成，最终决定了 治愈过程的成功(或失败)。因此，我们提出了假设 在骨折愈合的早期阶段，由于 不可避免地破坏骨骼的血液供应，导致缺氧 因子I(HIF-1a)，它反过来上调转录的级联 直接促进血管生成的下游基因。这样做的目的是 为期三年的研究是为了检验这样一种假设，即 转录因子，HIF-1a，是建立 软骨形成区和软骨内骨化区的新生血管形成 在骨折的骨痂中。我们的初步数据显示，HIF-1a以及 血管生成相关基因(即血管内皮生长因子)的数量 [血管内皮生长因子]、细胞色素R61)在骨折愈合阶段上调， 为我们的假设提供了强有力的支持证据。实验将是 通过以下四个具体目标系统地扩展这些发现 利用所建立的体内股骨骨折模型来确定 缺氧诱导因子-1a(II)靶基因的时空表达水平 已知在血管生成(血管内皮生长因子)、血管扩张(一氧化氮)中起作用 合成酶NOS、血红素加氧酶HO1与红细胞生成(EPO、RPO、 转铁蛋白)，并直接比较(III)血管生成 (4)结构完整性(强度和刚度) HIF-1a部分骨折骨痂和愈合股骨的实验研究 缺乏野生型(+/+)后代的(+/-)小鼠。这些 研究将为关键的早期事件提供独特的见解，并有助于 确定可能导致延迟发生的病因因素 愈合，特别是在分子成分的情况下(即低氧诱导因子-L a) 参与缺氧和血管生成。

DESCRIPTION (Taken from the application): Despite a wealth of information regarding hypoxia and angiogenesis during fracture repair, the underlining molecular events responsible for these critical early processes remain unknown. With the recent technological advances in molecular biology and the identification of thousands of genes, it is now possible to more clearly examine the precise molecular events that underlie the fracture repair process. In essence, we strongly believe that key early stage processes, including hypoxia and angiogenesis, are ultimately responsible for determining the success (or failure) of the healing process. Thus, we propose the hypothesis that during the early stages of fracture healing, hypoxia resulting from the inevitable disruption of the bone's blood supply, induces hypoxia inducible factor I (HIF-1a), which in turn up-regulates transcription of a cascade of downstream genes that directly promote angiogenesis. The objective of this three year study is to test the hypothesis that the up-regulation of the transcription factor, HIF-la, is critical to the establishment of neovascularization within areas of chondrogenesis and endochondral ossification in the fracture callus. Our preliminary data show that HIF-la, as well as a number of angiogenic-related genes (i.e. vascular endothelial growth factor [VEGF], CYR61), are up-regulated during the stages of fracture healing, providing strong supporting evidence for our hypothesis. Experiments will be performed to systematically extend these findings through four specific aims that utilize the established in vivo femur fracture model to determine the temporal and spatial expression levels of: (i) HIF-1a (ii) its target genes known to play a role in angiogenesis (VEGF), vasodilation (nitric oxide synthase NOS, heme oxygenase HO1, and erythopoiesis (erythropoietin RPO, tranferrin), and to directly compare the (iii) angiogenesis (neovascularization) and (iv) structural integrity (strength and stiffness) of the fracture callus and healing femurs, respectively, in HIF-1a partially deficient (+/-) mice to that of their wild type (+/+) littermates. These studies will provide unique insight into critical early-stage events, and help define etiologic factors that may contribute to the incidence of delayed healing, particularly in the case of the molecular components (i.e. HIF-l a) involved in hypoxia and angiogenesis.